Recently developed fast integral equation methods for computing solutions to the Stokes' equation have proven to be a valuable tool for micro-machined device designers. The speed of these fast codes make it possible to simulate multiple interacting 3-D structures, but issues associated with the singularity of the integral form of Stokes' equation have not been suÆciently carefully addressed to reliably perform such simulations. In this paper we describe the issue and show a remedy.